1. Field of the Invention
The present invention relates to a liquid spraying apparatus which sprays an image forming solvent as a liquid onto image recording materials such as a photosensitive material and an image receiving material.
2. Description of the Related Art
Generally, an image forming apparatus using a laser exposure heat developing and transferring system (i.e., a silver salt photographing system) is used. In such an image forming apparatus, prints are output in the processing steps as shown in FIG. 14. First, in an exposure processing step, image processing is carried out on an image data input signal by a CPU 500. The signal which has been subjected to the image processing is transmitted to a semi-conductor unit 502.
In this semi-conductor unit 502, by using a laser (LD) light source, a three-color simultaneous exposure process is carried out on the exposure surface of a donor piece 506 which has been pulled out from a donor roll 504 onto which a donor material is wound in the form of a roll, and cut to a predetermined length. By this exposure process, silver halide contained in the donor piece 506 reacts with the light source, a static image is formed, and fed to a water application step.
In this water application step, a predetermined, small amount of water is uniformly applied to the surface of the donor piece 506 by a liquid spraying apparatus 508, and the donor piece 506 having water thus applied thereto is fed to a heat developing and color image transferring step.
In this heat developing and color image transferring step, in a state in which an image receiving paper strip 512 (an OHP film or the like can also be used) which has been pulled out and cut to a predetermined length from an image receiving paper roll 510, and the donor piece 506 onto which water is applied are laminated with each other, the laminated image receiving paper strip 512 and the donor piece 506 are heated by a heating device 514. Therefore, a developing process is carried out on the donor piece 506, while dyes on the donor piece 506 are transferred to the image receiving paper strip 512, and fixed thereto. Accordingly, an image on the donor piece 506 is transferred to the image receiving paper strip 512. After this transferring operation has been completed, the laminated image receiving paper strip 512 and donor piece 506 are fed to a peel-off step.
In this peel-off step, the donor piece 506 which has been used, and the image receiving paper strip 512 onto which an image has been transferred are peeled off from each other, the donor piece 506 is then abandoned, and the image receiving paper strip 512 is finished as a high quality color print, and thereby outputted.
Conventionally, as a liquid spraying apparatus 508 which is used for such an image forming apparatus as described above, a liquid spraying apparatus has been proposed. In this apparatus, in order to uniformly apply a small amount of water to the surface of the donor piece 506, a nozzle plate in which a number of small nozzle holes are punched is disposed at the bottom of a sealed water tank to which water is supplied from outside. A small columnar actuator is provided at a predetermined distance from the nozzle plate in the lengthwise direction thereof. The nozzle plate is vibrated by driving the actuator, the water in the water tank, as water droplets, is sprayed from the nozzle holes of the nozzle plate to the outside.
In the above-described liquid spraying apparatus 508, at the beginning of use of the apparatus, water is supplied from a water supplying pipe and the internal portion of an empty water tank is filled with the water. During the operation of spraying water onto the donor piece 506, the same amount of water is supplied from the water supplying pipe to the sealed type water tank as that lost each time it is sprayed so that the water pressure in the tank can be kept constant. Further, when the operation of applying water to the donor piece 506 by means of the liquid spraying apparatus 508 has been completed, water in the water tank is drained from a drain pipe so that water leakage from the nozzle holes is prevented when the liquid spraying apparatus 508 is not in use.
In such a liquid spraying apparatus which has been proposed conventionally as described above, during use thereof, when an empty water tank is filled with water, the internal wall of the water tank may be deposited with bubbles, and some of these may remain as residual bubbles.
In this way, if residual bubbles exist inside the sealed type water tank, when the nozzle plate is vibrated by driving the actuator, and the nozzle plate moves in the direction in which the pressure in the water tank increases, the volume of the bubbles contracts so as to absorb the pressure in the water tank. Or when the nozzle plate moves in the direction in which the pressure in the water tank decreases, the volume of the bubbles expands so as to absorb the pressure in the water tank. Accordingly, pressure loss is caused. As a result, there are drawbacks in that the pressure for pressurizing the water in the sealed type water tank by the nozzle plate decreases, water cannot be pushed out and sprayed from the nozzle holes, and atomization failure may be caused.
In view of the aforementioned facts, it is an object of the present invention to provide a liquid spraying apparatus in which, when a liquid tank having a nozzle plate is filled with a liquid, the internal portion of the liquid tank is prevented from being deposited with residual bubbles, and a liquid can be sprayed appropriately from the liquid tank without causing atomization failure.
In accordance with a first aspect of the present invention, there is provided a liquid spraying apparatus in which a nozzle plate, which is provided at a portion of the wall surface of a spray tank which stores a liquid therein, and which has a row of nozzles made up of a plurality of nozzle holes through which a liquid is sprayed, is reciprocated so that the liquid inside the spray tank is pressurized and sprayed from the plurality of nozzle holes, comprising: a bubble detecting means which, when the spray tank is filled with a liquid, detects whether residual bubbles exist inside the spray tank.
Since the present invention is structured as described above, at the start of using the liquid spraying apparatus, when the spray tank is filled with a liquid, if residual bubbles exist inside the spray tank, the bubble detecting means detects that residual bubbles exist in the spray tank. In this case, for example, by a user performing a manual operation in which a liquid is drained from the spray tank so as to drain out residual bubbles therefrom and the spray tank is refilled with a liquid, residual bubbles are removed from the spray tank, and without causing atomization failure, a liquid can be sprayed appropriately from the spray tank.
In accordance with a second aspect of the present invention, there is provided a liquid spraying apparatus in which a nozzle plate, which is provided at a portion of the wall surface of a spray tank which stores a liquid therein, and which has a row of nozzles made up of a plurality of nozzle holes through which a liquid is sprayed, is reciprocated so that the liquid inside the spray tank is pressurized and sprayed from the plurality of nozzle holes, comprising: bubble detecting means which, when the spray tank is filled with a liquid, detects whether or not residual bubbles exist inside the spray tank; and residual bubble prevention and control means which, when receiving a signal indicating that the existence of residual bubbles has been detected by the bubble detecting means, drains the residual bubbles.
Since the present invention is structured as described above, after the spray tank has been filled with a liquid, when the existence of residual bubbles has been detected by the bubble detecting means, a control operation in which the liquid inside the spray tank is drained so as to drain out residual bubbles, and the spray tank is refilled with a liquid is automatically carried out. Alternatively, a control operation comprising: means in which residual bubbles are removed by tilting the spray tank; means in which residual bubbles are removed by decreasing the pressure of the liquid with which the spray tank is filled; and means in which residual bubbles are removed by stirring the liquid with which the spray tank is filled, and the like are carried out automatically. As a result, residual bubbles are removed from the spray tank, and a liquid can be sprayed appropriately from the spray tank without causing atomization failure.
In accordance with a third aspect of the present invention, there is provided a liquid spraying apparatus in which a nozzle plate, which is provided at a portion of the wall surface of a spray tank which stores a liquid therein, and which has a row of nozzles made up of a plurality of nozzle holes through which a liquid is sprayed, is reciprocated so that the liquid inside the spray tank is pressurized and sprayed from the plurality of nozzle holes, comprising: bubble detecting means which, when the spray tank is filled with a liquid, detects whether or not residual bubbles exist inside the spray tank; and residual bubble prevention and control means which, when receiving a signal indicating that the existence of residual bubbles has been detected by the bubble detecting means, carries out a control operation in which the liquid with which the spray tank is filled is drained, and the spray tank is refilled with a liquid.
Since the present invention is structured as described above, after the spray tank has been filled with a liquid, when the existence of residual bubbles has been detected by the bubble detecting means, a control operation is automatically performed in which the liquid with which the spray tank is filled is drained, and the spray tank is refilled with a liquid. As a result, residual bubbles are removed from spray tank, and a liquid can be sprayed appropriately from the spray tank without causing atomization failure.